There's $18 million riding on this massive video game tournament that's happening right now

If you don't know what that means, you're not alone. But its a big deal, with $18 million (and counting) on the line.

The prize pool for The International 5 as of Tuesday morning. Valve

Video games, like soccer, baseball, and football, have their professional athletes - extremely skilled players who other fans will spend hours watching play.

Pretty much any game can be an eSport. There are even professional "Super Smash Bros." players. But by far the biggest game in eSports is "Dota 2," a free game from the company behind other popular titles like "Portal" and "Half-Life." The International is its official annual tournament. And it has all the pomp and circumstance of a major sports event.

Here's a player prepping before a match:

And here's what it looks like with two teams on stage:

"Dota 2" can be a bit technical, but there are still people who love to watch even though they never play themselves.

Valve broadcasts the tournament to theaters and streams it online. You can also find a newcomers' stream with entry-level commentary on its website. If you live in Seattle, you can buy tickets to watch live at the KeyArena.

For a taste of the action, here's a match from day one of the tournament between teams Na'Vi and Vega Squadron. (Warning: the commentary on this video is geared toward long-time fans and can be a bit opaque if you're a new to this world.)